1. Technical Field
The present invention relates to novel carboxymethylmannoglucans and derivatives and salts thereof. More particularly, the present invention is concerned with a carboxymethylmannoglucan and derivatives and salts thereof for use as a carrier useful for delaying the disappearance of a drug in the blood and for enhancing the organotropism of the drug for a carcinoma.
2. Background Art
An attempt to use a water-soluble polymer as a carrier for a drug has hitherto been made especially in the field of a pharmaceutical preparation, and many related techniques for this purpose have been proposed in the art. In many of these proposals, use is made of cellulose derivatives such as carboxymethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methylcellulose, and the dispersion and sustained release of the drug are intended by virtue of physical and chemical properties of these substances per se. While in these attempts the drug is mixed homogeneously with the cellulose derivatives as a carrier, the drug is not chemically bonded to the carrier.
In the so-called "technique for organotropism" wherein a drug is delivered by a necessary amount at a desired time to a target organ, when a water-soluble polymer is utilized as a carrier for a drug, the drug and the carrier should be chemically bonded to each other rather than mere mixing. Examples of such attempts include bonding of mitomycin C to dextran (Hitoshi Sezaki, Yakugaku Zasshi, 109, 611-621 (1989)), bonding of mitomycin C to mannan (Report in the 49th General Meeting of The Japanese Cancer Association, (1990), page 425, theme No. 2155), bonding of bleomycin to mannan (Report in the 49th General Meeting of The Japanese Cancer Association, (1990), page 425, theme No. 2154), etc. The present status, however, is that no sufficient development is made on the technique wherein a polysaccharide type water-soluble polymer is newly synthesized and a drug is chemically bonded to this polymer to deliver the drug.